Follow-up Colonoscopy Lowers Mortality in Colorectal Cancer Patients

SEATTLE—Having at least one follow-up colonoscopy within 5 years of a diagnosis of nonmetastatic colorectal cancer decreased the mortality risk by 40%, according to a study presented at the 67th Annual Scientific Meeting of the American College of Gastroenterology (president’s plenary session abstract 11).

Lead author Deborah Fisher, MD, an associate in the Department of Medicine, Duke University, said that the study supports the current practice of performing endoscopic surveillance in this group of patients and is the first to show a mortality benefit. In collaboration with colleagues from Duke University and the Durham VA Medical Center, Dr. Fisher utilized three national VA databases—the inpatient treatment file, the outpatient clinic file, and the beneficiary identification and records location system (BIRLS)—to find a suitable study cohort.

While the optimal study design would be a randomized controlled trial, Dr. Fisher said, the researchers decided on a retrospective cohort design because of the expense and large enrollment needed for a randomized trial, along with the fact that randomizing patients to no colonoscopy follow-up would contradict current guidelines.

A total of 3,546 patients were included in the study. They were 98% male and 81% white, with a mean age of 68 years. Patients were included if they had a diagnosis of colon or rectal cancer in fiscal years 1995 to 1996, and were excluded if there was any history of inflammatory bowel disease, metastatic disease at initial diagnosis, death within 1 year of initial diagnosis, and race other than black or white.

Approximately half of the patients had no major comorbidities, 26% had one, and 19% had two or more. A total of 28% received chemotherapy, and 16% radiation therapy. The 5-year survival rate was 67%, and 64% had undergone at least one follow-up colonoscopy. Patients in both groups (with or without follow-up colonoscopy) averaged 123 outpatient visits for any reason.

The researchers found that demographics, such as age and race, and distribution of comorbidities were similar between patients who underwent a follow-up colonoscopy and those who did not. "There were, however, significantly more patients in the follow-up group who received chemotherapy and radiation therapy," Dr. Fisher said.

Using the log rank test, the 5-year survival rate was found to be significantly higher for the follow-up colonoscopy group (P < .0001). Analysis by the Cox proportional hazard method also showed that colonoscopy was associated with a significant decrease in risk of death at any point during the 5-year follow-up (risk ratio 0.6).

Other Factors

Age and increasing comorbidity also affected the mortality risk. At 5 years, age was associated with an increased risk of death (risk ratio 1.1 for each 5 years in age). For patients with a major comor-bidity, compared with those with no major comorbidities, the risk ratio was 1.4, and for patients with two or more comor-bidities, the risk ratio increased to 1.9.

Race and tumor site were not significantly associated with an increased risk of mortality, but both chemotherapy and radiation therapy were. This likely reflected more advanced disease in patients receiving this treatment, Dr. Fisher said.

"Overall medical utilization, which was measured by the total number of outpatient visits, was similar between the two groups," she said. This suggests that the reduced mortality risk was associated with colonoscopy itself and not with more intensive follow-up among the colonoscopy patients.